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Quick intro about Yeast
this page is currently a work in progress Saccharomyces Cerevisiae - aka yeast learn lots about yeast on the SGD wiki http://wiki.yeastgenome.org/index.php/What_are_yeast%3F lots of tools are available at SGD -> http://www.yeastgenome.org/ *General Yeast info *Mating info http://en.wikipedia.org/wiki/Mating_of_yeast, note that BY has been engineered to not undergo mating type switching *'Growth media' Yeast need Carbon Nitrogen Phosphate Oxygen and Hydrogen Oxygen 'from the air - note that S.cerevisiae are commonly stated to be faculative anerobes but that has been disputed. "It only grows for a few generations without air and does not obtain much energy from respiration during its aerobic growth on sugars" (see http://www.sciencedirect.com/science/article/pii/0968000481900736). They need oxygen for synthesis of egersterol (sort of the yeast version of cholesterol). C N P H from growth media There are two main types of growth media - "rich" or YPD (or really yeast extract and peptone based) YEP - 1% '''y'east 'e'xtract, 2% bacto 'p'eptone, Yeast extract is what is sounds like, the extract of yeast thus it contains many nutrients yeast would normally use to grow Peptone - is an enzymatic digest of animal protein (thus is a source of Nitrogen, at least partially via amino acids e.g., glutamate, glutamine, proline) to make solid media, 2% agar is added Agar - "is a gelatinous substance derived by boiling a polysaccharide in red algae, where it accumulates in the cell walls of agarophyte and serves as the primary structural support for the algae's cell walls" (from wikipedia) see more specifics of media here, particularly "Synthetic media" Commonly used media terms / abbreviations YPD (aka YEPD)- yeast extract, peptone, and 2% 'D'extrose (aka glucose), '''Carbon '''source YPG - YEP + 3% glycerol - glycerol is three carbons each with a OH attached typcially synthetic media is made lacking one or more amino acids and names minus aminoacid (e.g., -HIS media does not have histidineadded) or nucleobase (e.g. -URA doesnt contain uracil). This is used for selection, so that yeast must have exogenously obtained (e.g., via plasmid or linear dna you introduce) a biosynthesis gene that the yeast have been engineered to lack For BY4742/4741 they lack the entire URA3 gene, LEU2 gene, and lack a chunk of the HIS3 gene) so BY cannot grow on media lacking uracil, histidine or leucine. About BY strain BY4743 - diploid, ura3delta0 leu2delta0 his3delta1 BY4742 - Matα''' MET15+ lys2- ura3 leu2 his3 haploid BY4741 Mat'A' LYS2+ MET15- ura3 leu2 his3 haploid This strain is derived from S288C, which is the strain you will commonly see on the SGD website Genotype: S288C SUC2 gal2 mal mel flo1 flo8-1 hap1 ho (from SGD) gal2 - ''Galactose permease, required for utilization of galactose; also able to transport glucose ''mal ? mel ? flo1 - ''lectin-like protein involved in '''flocculation'; cell wall protein that binds mannose chains on the surface of other cells, confers floc-forming ability (probably decreases aggregation of the yeast) flo8-1 ''Transcription factor required for '''flocculation', diploid filamentous 'growth, and haploid '''invasive '''growth; genome reference strain S288C and most laboratory strains have a nonsense mutation in this gene ''hap1 - '''zinc finger transcription factor involved in the complex regulation of gene expression in response to levels of heme and oxygen; the S288C sequence differs from other strain backgrounds due to a Ty1 insertion in the carboxy terminus' - although it is partially functional, ('this mutation is not by design) ho - ''HO endonuclease required for mating type switching (keeps MATA cells A and alpha cells alpha)'' BY4743 - MAT''a/α ''his3Δ''1/his3''Δ''1 leu2''Δ''0/leu2''Δ''0 LYS2/lys2''Δ''0 met15''Δ''0/MET15 ura3''Δ''0/ura3''Δ''0'' mip1 variant - mitochondrial DNA polymerase ('''this mutation is not by design) notes about gene deletions: ura3 deleted and ~295bp upstream? ~75bp downstream; *need to reverify this* his3 only small region deleted, illustrated below